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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

26336 results found.

  1. Konus-Wind detection of GRB 260617A
  2. GRB 260616B: AstroSat CZTI detection
  3. GRB 260616A: AstroSat CZTI detection
  4. GRB 260616A: SVOM/GRM observation
  5. EP260618a: OHP/T193 optical observations
  6. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  7. GRB 260619A: Kilonova-Catcher optical upper limit
  8. EP260618a: LCO optical counterpart confirmation
  9. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  10. EP260618a: COLIBRÍ optical counterpart candidate
  11. GRB 260616A: NuSTAR detection of prompt emission
  12. GRB 260614B: NuSTAR detection of prompt emission
  13. GRB 260619A: SVOM possible detection of a faint burst
  14. GRB 260618B: Fermi-LAT detection
  15. IPN triangulation of GRB 260617A (short)
  16. GRB 260616A: Insight-HXMT detection
  17. EP260618a: EP-WXT detection of an X-ray transient
  18. GRB 260506B: cubesat Avion detection
  19. GRB 260616C: GECAM-B observation of a burst
  20. GRB 260617A: Fermi GBM Detection
  21. GRB 260616A: Fermi GBM Observation
  22. Konus-Wind detection of GRB 260616B/EP260616a
  23. Konus-Wind detection of GRB 260616A
  24. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  25. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  26. GRB 260616A: GECAM-B observation
  27. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  28. GRB 260429A: cubesat Avion detection
  29. GRB 260616A: Fermi-LAT detection
  30. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  31. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  32. GRB 260614A: AstroSat CZTI detection
  33. EP260616a: EP-WXT detection of a fast X-ray transient
  34. GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
  35. GRB 260616B: Fermi GBM Detection
  36. GRB 260604C: GRANDMA late observations with CFHT/MegaCam
  37. GRB 260614B: SVOM/ECLAIRs refined analysis
  38. GRB 260614B: GECAM-B observation
  39. GRB 260610B: SVOM/GRM observation
  40. GRB 260614B: SVOM/VT optical afterglow confirmation
  41. GRB 260614B: Fermi GBM Observation
  42. GRB 260614A: GECAM-B observation
  43. GRB 260614B: SVOM/VT optical candidate from VHF data
  44. GRB 260614B: SVOM detection of a burst
  45. GRB 260611B: SVOM/GRM detection
  46. GRB 260603C: AstroSat CZTI detection
  47. GRB 260610B: further Liverpool Telescope optical observations
  48. GRB 260610B: Fermi GBM Observation
  49. GRB 260610B / AT2026owq: GRANDMA optical observations
  50. GRB 260610B / AT2026owq: further SAO RAS optical observations
  51. EP260605a: COLIBRÍ optical upper limits
  52. GRB 260610b: Liverpool Telescope optical observations
  53. IceCube-260610A: No candidates from the Zwicky Transient Facility
  54. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  55. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  56. GRB 260610B / AT2026owq: SVOM/VT optical observations
  57. GRB 260610B / AT2026owq: SAO RAS optical observations
  58. GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
  59. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  60. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  61. GRB 260610B / AT2026owq: Early ATLAS observations
  62. GRB 260610B: TRT optical observation
  63. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  64. EP260610b: COLIBRÍ optical observations
  65. GRB 260610B: DDOTI optical observations
  66. EP260610b: MAO/AZT-22 optical observations
  67. GRB 260610B: GOTO optical counterpart candidate
  68. EP260610b: NOT optical observation
  69. EP260610b: SVOM/VT optical confirmation with blue color
  70. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 260515A: SOAR optical observations
  72. EP260610b: Gemini North optical counterpart candidate
  73. EP260610a: SVOM/VT optical upper limits
  74. EP260610b: Einstein Probe detection of an X-ray transient
  75. Konus-Wind detection of GRB 260601A
  76. IPN triangulation of GRB 260601A (short/hard)
  77. EP260610a: COLIBRÍ optical upper limits
  78. EP260610a: Einstein Probe detection of a fast X-ray transient
  79. Konus-Wind detection of GRB 260604C
  80. GRB 260608A: Fermi GRB Observation
  81. GRB 260604C: AstroSat CZTI detection
  82. IPN triangulation of GRB 260601B / EP260601a
  83. GRB 260604C: SVOM/ECLAIRs refined analysis
  84. GRB 260608A: SVOM/ECLAIRs refined analysis
  85. Konus-Wind detection of GRB 260607B
  86. GRB 260607B: GECAM-B observation
  87. GRB 260604C: further SAO RAS optical observations
  88. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  89. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  90. GRB 260604C: SVOM/C-GFT upper limit
  91. GRB 260607B: AstroSat CZTI detection
  92. GRB 260608A: SVOM detection of a burst
  93. EP260605a: EP-FXT follow-up observation
  94. GRB 260607A: TRT optical observations
  95. GRB 260604C: GRANDMA further observations
  96. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  97. GRB 260604A: SVOM/GRM detection
  98. GRB 260607B: Fermi GBM Observation
  99. GRB 260607B: Fermi-LAT detection
  100. GRB 260607B: Fermi GBM Final Localization Correction

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